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authorZack Weinberg <zackw@panix.com>2017-06-08 15:39:03 -0400
committerZack Weinberg <zackw@panix.com>2017-06-08 15:39:03 -0400
commit5046dbb4a7eba5eccfd258f92f4735c9ffc8d069 (patch)
tree4470480d904b65cf14ca524f96f79eca818c3eaf /REORG.TODO/sysdeps/posix/tempname.c
parent199fc19d3aaaf57944ef036e15904febe877fc93 (diff)
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Prepare for radical source tree reorganization. zack/build-layout-experiment
All top-level files and directories are moved into a temporary storage
directory, REORG.TODO, except for files that will certainly still
exist in their current form at top level when we're done (COPYING,
COPYING.LIB, LICENSES, NEWS, README), all old ChangeLog files (which
are moved to the new directory OldChangeLogs, instead), and the
generated file INSTALL (which is just deleted; in the new order, there
will be no generated files checked into version control).
Diffstat (limited to 'REORG.TODO/sysdeps/posix/tempname.c')
-rw-r--r--REORG.TODO/sysdeps/posix/tempname.c305
1 files changed, 305 insertions, 0 deletions
diff --git a/REORG.TODO/sysdeps/posix/tempname.c b/REORG.TODO/sysdeps/posix/tempname.c
new file mode 100644
index 0000000000..b00bd588ec
--- /dev/null
+++ b/REORG.TODO/sysdeps/posix/tempname.c
@@ -0,0 +1,305 @@
+/* Copyright (C) 1991-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#if !_LIBC
+# include <config.h>
+# include "tempname.h"
+#endif
+
+#include <sys/types.h>
+#include <assert.h>
+
+#include <errno.h>
+#ifndef __set_errno
+# define __set_errno(Val) errno = (Val)
+#endif
+
+#include <stdio.h>
+#ifndef P_tmpdir
+# define P_tmpdir "/tmp"
+#endif
+#ifndef TMP_MAX
+# define TMP_MAX 238328
+#endif
+#ifndef __GT_FILE
+# define __GT_FILE	0
+# define __GT_DIR	1
+# define __GT_NOCREATE	2
+#endif
+#if !_LIBC && (GT_FILE != __GT_FILE || GT_DIR != __GT_DIR	\
+	       || GT_NOCREATE != __GT_NOCREATE)
+# error report this to bug-gnulib@gnu.org
+#endif
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <fcntl.h>
+#include <sys/time.h>
+#include <stdint.h>
+#include <unistd.h>
+
+#include <sys/stat.h>
+
+#if _LIBC
+# define struct_stat64 struct stat64
+# define __secure_getenv __libc_secure_getenv
+#else
+# define struct_stat64 struct stat
+# define __gen_tempname gen_tempname
+# define __getpid getpid
+# define __gettimeofday gettimeofday
+# define __mkdir mkdir
+# define __open open
+# define __lxstat64(version, file, buf) lstat (file, buf)
+# define __secure_getenv secure_getenv
+#endif
+
+#ifdef _LIBC
+# include <hp-timing.h>
+# if HP_TIMING_AVAIL
+#  define RANDOM_BITS(Var) \
+  if (__glibc_unlikely (value == UINT64_C (0)))				      \
+    {									      \
+      /* If this is the first time this function is used initialize	      \
+	 the variable we accumulate the value in to some somewhat	      \
+	 random value.  If we'd not do this programs at startup time	      \
+	 might have a reduced set of possible names, at least on slow	      \
+	 machines.  */							      \
+      struct timeval tv;						      \
+      __gettimeofday (&tv, NULL);					      \
+      value = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec;		      \
+    }									      \
+  HP_TIMING_NOW (Var)
+# endif
+#endif
+
+/* Use the widest available unsigned type if uint64_t is not
+   available.  The algorithm below extracts a number less than 62**6
+   (approximately 2**35.725) from uint64_t, so ancient hosts where
+   uintmax_t is only 32 bits lose about 3.725 bits of randomness,
+   which is better than not having mkstemp at all.  */
+#if !defined UINT64_MAX && !defined uint64_t
+# define uint64_t uintmax_t
+#endif
+
+#if _LIBC
+/* Return nonzero if DIR is an existent directory.  */
+static int
+direxists (const char *dir)
+{
+  struct_stat64 buf;
+  return __xstat64 (_STAT_VER, dir, &buf) == 0 && S_ISDIR (buf.st_mode);
+}
+
+/* Path search algorithm, for tmpnam, tmpfile, etc.  If DIR is
+   non-null and exists, uses it; otherwise uses the first of $TMPDIR,
+   P_tmpdir, /tmp that exists.  Copies into TMPL a template suitable
+   for use with mk[s]temp.  Will fail (-1) if DIR is non-null and
+   doesn't exist, none of the searched dirs exists, or there's not
+   enough space in TMPL. */
+int
+__path_search (char *tmpl, size_t tmpl_len, const char *dir, const char *pfx,
+	       int try_tmpdir)
+{
+  const char *d;
+  size_t dlen, plen;
+
+  if (!pfx || !pfx[0])
+    {
+      pfx = "file";
+      plen = 4;
+    }
+  else
+    {
+      plen = strlen (pfx);
+      if (plen > 5)
+	plen = 5;
+    }
+
+  if (try_tmpdir)
+    {
+      d = __secure_getenv ("TMPDIR");
+      if (d != NULL && direxists (d))
+	dir = d;
+      else if (dir != NULL && direxists (dir))
+	/* nothing */ ;
+      else
+	dir = NULL;
+    }
+  if (dir == NULL)
+    {
+      if (direxists (P_tmpdir))
+	dir = P_tmpdir;
+      else if (strcmp (P_tmpdir, "/tmp") != 0 && direxists ("/tmp"))
+	dir = "/tmp";
+      else
+	{
+	  __set_errno (ENOENT);
+	  return -1;
+	}
+    }
+
+  dlen = strlen (dir);
+  while (dlen > 1 && dir[dlen - 1] == '/')
+    dlen--;			/* remove trailing slashes */
+
+  /* check we have room for "${dir}/${pfx}XXXXXX\0" */
+  if (tmpl_len < dlen + 1 + plen + 6 + 1)
+    {
+      __set_errno (EINVAL);
+      return -1;
+    }
+
+  sprintf (tmpl, "%.*s/%.*sXXXXXX", (int) dlen, dir, (int) plen, pfx);
+  return 0;
+}
+#endif /* _LIBC */
+
+/* These are the characters used in temporary file names.  */
+static const char letters[] =
+"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
+
+/* Generate a temporary file name based on TMPL.  TMPL must match the
+   rules for mk[s]temp (i.e. end in "XXXXXX", possibly with a suffix).
+   The name constructed does not exist at the time of the call to
+   __gen_tempname.  TMPL is overwritten with the result.
+
+   KIND may be one of:
+   __GT_NOCREATE:	simply verify that the name does not exist
+			at the time of the call.
+   __GT_FILE:		create the file using open(O_CREAT|O_EXCL)
+			and return a read-write fd.  The file is mode 0600.
+   __GT_DIR:		create a directory, which will be mode 0700.
+
+   We use a clever algorithm to get hard-to-predict names. */
+int
+__gen_tempname (char *tmpl, int suffixlen, int flags, int kind)
+{
+  int len;
+  char *XXXXXX;
+  static uint64_t value;
+  uint64_t random_time_bits;
+  unsigned int count;
+  int fd = -1;
+  int save_errno = errno;
+  struct_stat64 st;
+
+  /* A lower bound on the number of temporary files to attempt to
+     generate.  The maximum total number of temporary file names that
+     can exist for a given template is 62**6.  It should never be
+     necessary to try all of these combinations.  Instead if a reasonable
+     number of names is tried (we define reasonable as 62**3) fail to
+     give the system administrator the chance to remove the problems.  */
+#define ATTEMPTS_MIN (62 * 62 * 62)
+
+  /* The number of times to attempt to generate a temporary file.  To
+     conform to POSIX, this must be no smaller than TMP_MAX.  */
+#if ATTEMPTS_MIN < TMP_MAX
+  unsigned int attempts = TMP_MAX;
+#else
+  unsigned int attempts = ATTEMPTS_MIN;
+#endif
+
+  len = strlen (tmpl);
+  if (len < 6 + suffixlen || memcmp (&tmpl[len - 6 - suffixlen], "XXXXXX", 6))
+    {
+      __set_errno (EINVAL);
+      return -1;
+    }
+
+  /* This is where the Xs start.  */
+  XXXXXX = &tmpl[len - 6 - suffixlen];
+
+  /* Get some more or less random data.  */
+#ifdef RANDOM_BITS
+  RANDOM_BITS (random_time_bits);
+#else
+  {
+    struct timeval tv;
+    __gettimeofday (&tv, NULL);
+    random_time_bits = ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec;
+  }
+#endif
+  value += random_time_bits ^ __getpid ();
+
+  for (count = 0; count < attempts; value += 7777, ++count)
+    {
+      uint64_t v = value;
+
+      /* Fill in the random bits.  */
+      XXXXXX[0] = letters[v % 62];
+      v /= 62;
+      XXXXXX[1] = letters[v % 62];
+      v /= 62;
+      XXXXXX[2] = letters[v % 62];
+      v /= 62;
+      XXXXXX[3] = letters[v % 62];
+      v /= 62;
+      XXXXXX[4] = letters[v % 62];
+      v /= 62;
+      XXXXXX[5] = letters[v % 62];
+
+      switch (kind)
+	{
+	case __GT_FILE:
+	  fd = __open (tmpl,
+		       (flags & ~O_ACCMODE)
+		       | O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
+	  break;
+
+	case __GT_DIR:
+	  fd = __mkdir (tmpl, S_IRUSR | S_IWUSR | S_IXUSR);
+	  break;
+
+	case __GT_NOCREATE:
+	  /* This case is backward from the other three.  __gen_tempname
+	     succeeds if __xstat fails because the name does not exist.
+	     Note the continue to bypass the common logic at the bottom
+	     of the loop.  */
+	  if (__lxstat64 (_STAT_VER, tmpl, &st) < 0)
+	    {
+	      if (errno == ENOENT)
+		{
+		  __set_errno (save_errno);
+		  return 0;
+		}
+	      else
+		/* Give up now. */
+		return -1;
+	    }
+	  continue;
+
+	default:
+	  assert (! "invalid KIND in __gen_tempname");
+	  abort ();
+	}
+
+      if (fd >= 0)
+	{
+	  __set_errno (save_errno);
+	  return fd;
+	}
+      else if (errno != EEXIST)
+	return -1;
+    }
+
+  /* We got out of the loop because we ran out of combinations to try.  */
+  __set_errno (EEXIST);
+  return -1;
+}